Rename PostCSS files to .pcss (#9013)

* Rename PostCSS files to `.pcss`

* Make Stylelint happy

* Delint

* Rename new files too

* delint

* Fix bad comment placement

res/css/views/rooms/_EditMessageComposer.pcss

@@ -0,0 +1,53 @@
+/*
+Copyright 2019 New Vector Ltd
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+.mx_EditMessageComposer {
+    --EditMessageComposer-padding-inline: 3px;
+
+    display: flex;
+    flex-direction: column;
+    max-width: 100%; // disable overflow
+    width: auto;
+    gap: 5px;
+    padding: 3px var(--EditMessageComposer-padding-inline);
+
+    .mx_BasicMessageComposer_input {
+        border-radius: 4px;
+        border: solid 1px $primary-hairline-color;
+        background-color: $background;
+        max-height: 200px;
+        padding: 3px 6px;
+
+        &:focus {
+            border-color: rgba($accent, 0.5); // Only ever used here
+        }
+    }
+
+    .mx_EditMessageComposer_buttons {
+        display: flex;
+        flex-flow: row wrap-reverse; // display "Save" over "Cancel"
+        justify-content: flex-end;
+        gap: 5px;
+        margin-inline-start: auto;
+
+        .mx_AccessibleButton {
+            flex: 1;
+            box-sizing: border-box;
+            min-width: 100px; // magic number to align the edge of the button with the input area
+        }
+    }
+}